In the companion paper (Zhang et al., 2020), we identified two types of calibration models (CMs) that have been widely used in polarimetric calibration algorithms with distributed targets. An optimal… Click to show full abstract
In the companion paper (Zhang et al., 2020), we identified two types of calibration models (CMs) that have been widely used in polarimetric calibration algorithms with distributed targets. An optimal method based on the covariance matching estimation technique (COMET), which we refer to as the O method, was used therein but without proof of its optimality. This article supplies the details on parameter estimation using the O method and proves that it is optimal in the mean-squared sense: No other estimate has a smaller mean-squared error. For data affected by the Faraday rotation (FR), the feasibility of the O method is analyzed. Numerical experiments are presented to compare the O method with existing methods and prove its optimality. The differences between the O method and another COMET-based calibration method are discussed. Moreover, we prove that estimating the distortion parameters while preserving the orientation angle is impossible, contrary to what is found by Ainsworth et al. (2006).
